Requirement of JAK/STAT and BMP Signaling for Interfollicular Stalk Morphogenesis in the Drosophila melanogaster Ovary

Mascaro, Alexandra Rose

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Year:: 2019
Contributor:: Mascaro, Alexandra Rose (creator); Wharton, Kristi (Advisor); DeLong, Alison (Reader); Wessel, Gary (Reader); Johnson, Mark (Reader); Brown University. Department of Molecular Biology, Cell Biology and Biochemistry (sponsor)
Genre:: theses
Subject:: Drosophila melanogaster; Cell signaling; BMP signaling; JAK/STAT; Ovaries
Extent:: xiii, 153 p.

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Abstract:: A key process in the formation of complex tissues and organisms is the decision of which cells to maintain. This is part of morphogenesis, which also includes processes such as cell migration, division, shape changes, and death. Programmed cell death, or apoptosis, not only eliminates cells that are damaged or dangerous, but also removes cells that are no longer needed in patterning or organogenesis. The number of cells comprising a tissue may be tightly regulated during organ development, and the decision of which cells to maintain is determined by the integration of multiple inputs, such as signal transduction cascades and transcription factors. We have investigated this phenomenon in a specialized group of somatic cells that comprise the interfollicular stalk in the Drosophila melanogaster ovary. The interfollicular stalk separates developing egg chambers, each of which will form one mature oocyte. We find that elimination of the interfollicular stalk after its initial formation through the experimental induction of cell death is sufficient to result in the fusion of adjacent egg chambers, disrupting proper oogenesis. Interestingly, we find that the number of cells in each interfollicular stalk is highly controlled, with cells undergoing apoptosis during normal development. The maintenance of stalk cells is regulated by both BMP and JAK/STAT signaling. A reduction in signaling from either pathway is sufficient to enhance stalk cell loss during oogenesis. Conversely, ectopic upregulation of either pathway abrogates the normal loss of cells. We see that stalk cell maintenance is dependent on both the expression of the BMP ligand Gbb in the interfollicular stalk cells themselves, as well as both Gbb and the JAK/STAT ligand Upd expressed in the polar cells, specialized cells that are important in the specification of different cell fates to adjacent follicle cells. Interestingly, we see that within the interfollicular stalk, these two signaling pathways influence one another’s output. Activation of JAK/STAT signaling results in increased expression of the BMP ligand Gbb, and inhibition of BMP signaling results in decreased JAK/STAT signaling activity. Thus, the integration of two signal transduction pathways promotes maintenance of the interfollicular stalk and ensures optimal oocyte production.
Notes:: Thesis (Ph. D.)--Brown University, 2019

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Mascaro, Alexandra Rose, "Requirement of JAK/STAT and BMP Signaling for Interfollicular Stalk Morphogenesis in the Drosophila melanogaster Ovary" (2019). Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:1129480/

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Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations

Theses and Dissertations for the Molecular Biology, Cell Biology, and Biochemistry department.
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